1. Field of the Invention
An invention explained in this patent specification relates to a technology for reducing horizontal cross talks generated in a liquid-crystal display apparatus. It is to be noted that embodiments of the present invention are a digital-signal processing apparatus, a liquid-crystal display apparatus, a digital-signal processing method adopted in the digital-signal processing apparatus and a computer program implementing the digital-signal processing method.
2. Description of the Related Art
At the present day, a liquid-crystal display apparatus is mounted in various kinds of electronic equipment. FIG. 1 is a diagram showing an equivalent circuit of a substrate module 1 composing a liquid-crystal display apparatus.
The substrate module 1 includes a pixel-array section 3 formed on a glass substrate and driving circuits which are an H shift register 5, an H switch section 7 and a V shift register 9 formed or mounted in the surroundings of the pixel-array section 3.
First of all, the configuration of the pixel-array section 3 is explained. The basic configuration of the pixel-array section 3 includes m gate lines 11(0) to 11(m-1), n data lines 13(0) to 13(n-1) and m-row×n-column matrix of pixels 15 each located at an intersection of one of m gate lines 11(0) to 11(m-1) and one of the n data lines 13(0) to 13(n-1).
It is to be noted that the pixel-array section 3 shown in the diagram of FIG. 1 is used for color displays. For this reason, in the diagram of FIG. 1, data lines for red, green and blue colors on a column i are denoted by notations 13(i)R, 13(i)G and 13(i)B respectively. The subscript i, which is a column number, has a value in the range 0 to (n−1). Sub-pixels for red, green and blue color are denoted by notations 15R, 15G and 15B respectively.
FIG. 2 is a diagram showing an equivalent circuit of the sub-pixel. The sub-pixel employs a thin-film transistor T1 functioning as a switch device, a storage capacitor Cs for storing a signal electric potential Vsig and a liquid-crystal element LC. The liquid-crystal element LC has a structure including a pixel electrode, a facing electrode and a liquid crystal sandwiched between the pixel electrode and the facing electrode 17.
The facing electrode (Vcom) 17 is an electrode common to all pixels 15 composing the pixel-array section 3. That is to say, the facing electrode is actually formed as a single electrode covering areas occupied by the facing electrodes of all the pixels composing the pixel-array section 3.
Next, the structure of the driving circuits is explained. The H shift register 5 is a circuit device for providing a timing to apply a signal electric potential Vsig on each data line 13. In the case of the pixel-array section 3 shown in the diagram of FIG. 1, the H shift register 5 actually generates driving signals each used for controlling operations to turn on and off one of complementary switches composing the H switch section 7. Each of the mutual-complementation switches employs an n-channel FET (Field Effect Transistor) and a p-channel FET and is connected to one of the data lines 13.
It is to be noted that, as generally known, the characteristic of a liquid crystal deteriorates if the liquid crystal is driven at the same polarity. For this reason, it is generally necessary to adopt a driving method by which the polarity of the signal electric potential Vsig is inverted each line and each field. Thus, the polarity of the signal electric potential Vsig supplied to one of the main electrodes of the complementary switch is changed each line and each field.
The V shift register 9 is a circuit device for generating signals each applied on a gate line provided for a row of sub-pixels 15 in order to generate a timing with which signal electric potentials Vsig are written onto the sub-pixels 15.